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  • Dynaco
  • 617 N. 41st St, Philadelphia, USA
  • No official website available
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Equipment[add model]

Dynaco manufactures or has manufactured the following equipment (click to expand models list):

Dynamic Speakers
Solid State Amplifiers
Valve Amplifiers

General information [contribute]

Dynaco is best known for its highly regarded Stereo 70 vacuum tube amplifier. Introduced in 1959, the 35 watt per channel Stereo 70 (or "ST-70") was sold until mid-1990. With more than 300,000 ST-70s produced, it is the most popular tube power amp ever made. Dynaco electronics were available either factory assembled or in do-it-yourself kits, Dynakits. Because of their excellent sound quality, low noise, and reasonable prices, Dynaco tube amps were often referred to as "the poor man's McIntosh." Even today, upgraded components, rebuild kits, and even a complete improved reproduction of the ST-70 is available.

Dynaco is also well known for its line of transistor components. Beginning in 1966 with the introduction of the Stereo 120 model power amplifier (60 watts/channel) and the PAT-4 preamplifier in 1967, the company affirmed its ability to design reliable solid state equipment at an affordable price. In the 1970s, the Stereo 400 was developed and marketed. This was a high power amplifier at 200 watts per channel that offered automatic protection circuitry to prevent electrical destruction of the loudspeaker. The FM-5 tuner was offered as was the SCA-80 integrated amplifier in the early 1970s time line. There was also the Dynaquad system which allowed the user to simulate a quadrophonic sound by using out of phase signals at the speaker terminals. It apparently was a success and offered good four-channel sound at budget price. Dynaco's solid-state kits were different from the popular Heathkit products (and Dynaco's own vacuum tube kits) because of their preassembled circuit boards. These boards were wired at the factory, tested and packaged with the unassembled chassis. The builder was left, largely, to attach the switches and controls to the chassis pieces, assemble the chassis and power supply and solder connecting wires to the circuit boards. This saved considerable time and reduced errors on the part of the builder.

Dynaco also distributed the famous SEAS 'A-Series' of bookshelf loudspeakers that were manufactured in Denmark, using input from Dynaco's David Hafler. The A-Series were marketed between 1970 and Dynaco's demise in the 1980s. The Dynaco A-25 model proved to be extremely successful, selling over 600,000 units. A modified aperiodic bass reflex design in a handsome wood cabinet, it combined quality sound reproduction with a budget price (under $100), making it highly competitive with much more expensive loudspeakers. The patented aperiodic (essentially non-resonant) woofer design utilized a highly-damped vent instead of a reflex port, whose acoustic resistance is very carefully controlled. The resistant venting action lowered the "Q" of the system and reduced impedance variation near resonance in the A-Series speakers. Dynaco followed the A-25 with the slightly larger A-35, which featured a dual-chambered, non-vented design in a walnut-veneered cabinet with even greater transparency and fidelity. Over time, Dynaco marketed a wide range of loudspeakers, ranging from the small A-10 model to the floor standing A-50 series. After some 30 years, these loudspeakers still command good prices in markets such as eBay, and are a testimonial to their quality.

Concurrent with A-25 production, Dynaco introduced a system whereby 4-channel sound could be easily derived from stereo material by using a rear channel speaker matrix. This "Dynaco patent" required a single resistor and a threeway potentiometer for the two rear speakers for generating sufficient phase difference signals for a feeling of ambience. The system worked best when the stereo sound had been recorded via two bidirectional microphones on the same spot. When microphone set-up changed to the use of multiple directional microphones and multitrack tape recording and postprocessing (i.c. in the CD era), the Dynaco patent lost its market value.

The Pan Orient Corporation (later Panor Corporation) acquired the Dynaco trademark in the early 1990s and began marketing electronic components with the Dynaco brand. Panor even reintroduced some of the older Dynaco designs. Among collectors, the Panor/Dynaco ST-70 is not as desirable in comparison to vintage ST-70s of the 1960s (the earliest ST-70s with cloth-covered transformer leads are the most sought-after models among audiophiles and collectors)

Bob Latino (February 22, 2009): Dynaco tube kits and parts are available from ..

http://www.Dynakitparts.com > Replacement and upgrade parts and boards available for nearly all Dynaco tube amplifiers

http://www.tubes4hifi.com > Replacement boards and other parts for Dynaco tube amps.

http://www.tubes4hifi.com/bob.htm > Brand new upgraded Dynaco tube amp KITS and WIRED amplifiers.

A discussion forum on rebuilding, repairing and restoration of all Dynaco tube gear is at > http://dynacotubeaudio.forumotion.com/basket-f2/

Refurbishing & modifications[contribute]

Bob Latino (January 1, 2010): The largest collection (30 manuals) of FREE Dynaco tube and solid state manuals on the internet may be found at the link below.


Curcio Audio website (December 2001): The Dynaco Repair, Upgrade and Modifications Center

The popularity of Dynaco tube equipment is without precedent. Thousands of Dynaco PAS preamps and Stereo 70 & Mark-3 Power Amplifiers were manufactured during the 1950's thru the 1970's. And today they are more popular than ever. And so it should be as they provided more value that any other audio component ever offered.
With all of these amps and preamps still in operation, many with most of the original parts, it is quite common to have the need to repair or simply upgrade the existing components.

We have complied a comprehensive collection of information and products to provide everything you need to repair, rebuild, upgrade, or extensively modify your Dynaco tube preamp or power amplifier. Our repair center below will guide you to identify and isolate the problem. Following the repair center section you will find products and services for your specific Dynaco component

The Dynaco Doctor, Repair Center

CAE is dedicated to helping you troubleshoot and repair your Dyna amp or preamp. To begin download the complete original manual for your ST-70, MK-3, MK-4, PAS Preamplifier, or FM-3 Tuner. Next, download a copy of our comprehensive Troubleshooting Guide - it will take you step by step to the source of the problem. If you like you can e-mail us with a description of the problem and we will respond with suggestions that specifically address your problem. Finally, if you prefer, you can send us your amp or preamp where we will both repair and certify it at our lab.

Once you have located the defect, contact us. CAE can provide you with an exact replacement or audiophile premium direct substitute parts. We now offer drop in modules to replace the original "Quad" electrolytic capacitor with a composite that increases the voltage rating and capacitance, includes the bias supply, and optionally allows you to use solid state rectification should you choose. If you would like to make small but highly effective modifications, consider all new upgrade amplifier modules. These designs employ simple and highly linear topology and deliver outstanding sonic gains for a very small investment. And of course for those wanting to extract the ultimate performance, we continue to offer our highly regarded Constant Current Differential Amplifier driver module and our HiSpeed LowZ regulated power supply modules for the ST-70 and MK-3.

Whatever path you choose, all of our solutions simply "drop-in" to the existing chassis and hole pattern - there are no strange appendages or dangling parts. And you can be assured that we have optimized the design for the most articulate and realistic audible performance while insuring the highest reliability.

As always, I encourage you to contact us with your comments, suggestions and questions

External links

Dynaco Unofffical site dedicated to vintage Dynaco products thanks to Greg Dunn's efforts!
Dynaco Doctor
Dynaco FM 3 Review
Dynaco Free Schematic Diagrams
Dynaco Mark 3 Lidstrom
Dynaco Products and Modification Overview
Dynaco ST 70 Amplifier Review
Dynaco Stereo 120 Power Amplifier
Dynaco stereo 70 Lidstrom
Dynaco Stereo 70 Adams Troubleshooting Tips
Dynaco Unofficial Home Page Greg's UnofficialDynaco Home Page
Greg's Unoffical Dynaco Home Page Greg's Unofficial Dynaco Home Page

Forum topics on Dynaco

The following topics regarding Dynaco in general can be found in the forums. Topics about specific models can be found on the model pages. If you want to start a new topic, click here.